From f56df58fe8a8615c75214ebe3424be3764651461 Mon Sep 17 00:00:00 2001
From: Sam Kleinman <garen@tychoish.com>
Date: Tue, 14 Dec 2021 16:30:06 -0500
Subject: [PATCH] testing,log: add testing.T logger connector (#7447)

---
 libs/log/testing.go | 56 ++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 50 insertions(+), 6 deletions(-)

diff --git a/libs/log/testing.go b/libs/log/testing.go
index 9894f6a50..b76bb77c6 100644
--- a/libs/log/testing.go
+++ b/libs/log/testing.go
@@ -1,10 +1,10 @@
 package log
 
 import (
-	"io"
-	"os"
 	"sync"
 	"testing"
+
+	"github.com/rs/zerolog"
 )
 
 var (
@@ -19,11 +19,11 @@ var (
 // NOTE:
 // - A call to NewTestingLogger() must be made inside a test (not in the init func)
 // because verbose flag only set at the time of testing.
+// - Repeated calls to this function within a single process will
+// produce a single test log instance, and while the logger is safe
+// for parallel use it it doesn't produce meaningful feedback for
+// parallel tests.
 func TestingLogger() Logger {
-	return TestingLoggerWithOutput(os.Stdout)
-}
-
-func TestingLoggerWithOutput(w io.Writer) Logger {
 	testingLoggerMtx.Lock()
 	defer testingLoggerMtx.Unlock()
 
@@ -39,3 +39,47 @@ func TestingLoggerWithOutput(w io.Writer) Logger {
 
 	return testingLogger
 }
+
+type testingWriter struct {
+	t testing.TB
+}
+
+func (tw testingWriter) Write(in []byte) (int, error) {
+	tw.t.Log(string(in))
+	return len(in), nil
+}
+
+// NewTestingLogger converts a testing.T into a logging interface to
+// make test failures and verbose provide better feedback associated
+// with test failures. This logging instance is safe for use from
+// multiple threads, but in general you should create one of these
+// loggers ONCE for each *testing.T instance that you interact with.
+//
+// By default it collects only ERROR messages, or DEBUG messages in
+// verbose mode, and relies on the underlying behavior of testing.T.Log()
+func NewTestingLogger(t testing.TB) Logger {
+	level := LogLevelError
+	if testing.Verbose() {
+		level = LogLevelDebug
+	}
+
+	return NewTestingLoggerWithLevel(t, level)
+}
+
+// NewTestingLoggerWithLevel creates a testing logger instance at a
+// specific level that wraps the behavior of testing.T.Log().
+func NewTestingLoggerWithLevel(t testing.TB, level string) Logger {
+	logLevel, err := zerolog.ParseLevel(level)
+	if err != nil {
+		t.Fatalf("failed to parse log level (%s): %v", level, err)
+	}
+	trace := false
+	if testing.Verbose() {
+		trace = true
+	}
+
+	return defaultLogger{
+		Logger: zerolog.New(newSyncWriter(testingWriter{t})).Level(logLevel),
+		trace:  trace,
+	}
+}